Sundin, 38, was the first European player made the overall No. 1 choice of the NHL draft when he was taken by Quebec in 1989. He spent four seasons with Quebec before joining the Maple Leafs for 13 seasons. He was with Vancouver last season.
"It was a tough decision," Sundin said at a news conference. "It's sad to tell you today that my career as a pro hockey player is over."
He also said Toronto would "always be my second home." The Maple Leafs made Sundin their captain from the 1997-98 season through 2007-08.
Sundin appeared in 1,346 NHL games and had 564 goals and 785 assists. The goal total is tied for 20th on the all-time NHL list. He was an eight-time All-Star selection.
Sundin also helped his native Sweden take the gold medal in the 2006 Winter Olympics.